Lathe.



STATES PATENT OFFICE.

J'EISIS SLOTNAES, OF GREFSEN, CHRISTIANIA, NORWAY.

Patented Apr. 9,1918.

LATHE.

1,261 963 Specification of Letters Patent.

No Drawing. Application Med January 15, 1917. Serialflm 142,539.

To all whom it may concern:

Be it known that I, JENs SLo'rNAns, citizen of Norway, resident of Grefsen, city of Christiania, and State of Norway, have invented certain new and useful Improvement in Lathes, of which the following is a specification.

The present invention relates to turning lathes and more especially to those having a threaded lead screw and a special feed-shaft.

It has already been proposed to provide turning lathes with two leading screws having difl'erent pitch in order to reduce the number of gear wheels in the ordinary change gear ox. However, in those cases, the lead screws were constructed according to one and the same screw system i. c. the pitch was measured in one and the same unit, ordinarily in English inches or fractions thereof.

At present many screws are made with a pitch measured in millimeters, and on that account it has been desirable to so arran e screw cutting lathes that screws with millimeter-pitch and inch pitch can be easily cut in one and the same machine. This problem has been solved by the gear box eing provided with a change wheel with 127 teeth, because one half inch equals 12.699889 or nearly 12.7 mm., the error being only about 0.001%.

According to my invention the same problem is solved in another still simpler manner. I provide not only the lead screw but also the feed shaft with screw threads of different pitch, and the novelty of my invention resides in this, that if the threads of the lead-screw are made with a itch measured in inches, I make the threa s of the feed shaft with a pitch measured in millimeters, or vice-verse.

The apron consequently must have two screw-locks, one made for inch-pitch and another made for millimeter-pitch. By means of a special change-mechanism between the locks, only one of the locks can be put into operation at a time.

M invention is illustrated by way of exempi e in the accompanying drawing, in which:

Figure 1 is a cross section along the line 1-1 in Fig. 2, showing the lead screw and feed screw of a lathe, while Fig. 2 shows a part of the lathe as seen from the right in Fig. 1.

lhe frame 1 is provided with the usual upper guiding rail 2 3 is the lead-screw, 4 the feed-shaft, provided with the longitudinal key groove 5, 6 the apron, 7, 8 the ordinary half-nuts for the lead-screw, 9, 10 the racks upon the nuts 7, 8 respectively, 11 the pinion engaging the racks for moving the nuts 7, 8 in opposite directions and 12 the pinion operating shaft provided with the outer handle 13. The half nut 14 for the feed-shaft 4 forms one integral part with the half-nut 8 for the screw 3. Besides, the arrangement is so devised that both the halfnuts 7 8 and the half-nut 14 are out of engagement with their respective screws as shown in Fig. 1, when the handle 13 is in its middle or neutral osition.

When the handl 13 is turned down, the half-nuts 7, 8 engage their screw 3, whereas the half-nut 14 remains disenga ed. When the handle 13 is turned up, the alf-nut 14 engages its screw 4, while the half-nuts 7, 8 become disengaged. Thus, it will be seen that both screws cannot be engaged by their cooperating half-nuts at the same time.

By the arrangement described above the advanta e is obtained that if millimeterthreads ave to be cut in an ordinary lathe havin a lead-screw with an inch-pitch, the use 0 the ordinary change-wheel with 127 teeth can be avoided. Further the screws may be engaged in any adjusted position without any fault arisin This latter is not possible in the ordinary Iathe having a leadscrew with an inch-pitch and a changewheel with 127 teeth.

According to my invention the lead-screw and feed-shaft should have the same number of revolutions. In such case the pitches most frequent] in use may be obtained by means of the c ange-wheels ordinarily used in a lathe. If the lathe is provided with a gear-box, the same advantages are obtained.

Late] one has frequently arranged a special fee shaft in the lathe in order to avoid a key-groove throu bout the length of..the lead-screw. In suc lathes the present arrangement ma be utilized easily by simply cuttlng threa s in the existing feed-shaft. At the same time, the lathe originally designed for cutting screws with an inch-pitch may aiwails be ready for use for cutting vided with the inch pitch and the other screwsiwifi 2a milIimeter-pitch. a with the pitch in millimeters. 10 Having now described my invention, what Signed at Christiania, State of Norway,

I claim as new and desire to secure by Letthis eighth day of December A. D. 1916.

5 ters Patent is: JENS SLOTNAES.

In a turnin lathe, the combination oi s. Witnesses: lead screw an a threaded feed-shaft having Am LAHM, threads of a different pitch, one being pro- Mnomzs Boone.

00pm of this patent my be obtained for an cant: mm, by addressing the "commissioner of 2mm.

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